Grease gun plunger assembly



Oct. 23, 1962 P. SUNDHOLM GREASE GUN PLUNGER ASSEMBLY Fi led March so, 1960 2 SheetsSheet 1 INVENTOR! 8 jka flpauf ATTORNEYS.

Oct. 23, 1962 E. P. SUNDH'OLM 3,059,980

GREASE GUN PLUNGER ASSEMBLY Filed March 30, 1960 2 Sheets-Sheet 2v wapfdmw BV W Z 7414 ATTORNEYS.

3,859,988 Patented Oct. 23, 1962 3,059,988 GREASE GUN PLUNGER ASSEMBLY Edwin F. Sundhohn, Albert City, Iowa Filed Mar. 30, 196i), Ser. No. 18,789 7 (Ilaims. (Cl. 3tl9--4) This invention relates to a plunger assembly for a grease gun. The plunger assembly of this invention is adapted for use with manual or lever-operated grease guns of the type shown in my prior Patent No. 2,915,226. The present application is a continuation-in-part of my application Serial No. 785,689, filed January 8, 1959, which application was copending with my application Serial No. 636,971, which resulted in Patent No. 2,915,226.

The principal object of this invention is to provide a grease gun plunger assembly of improved construction from any that has heretofore been known. My improved plunger assembly is simpler and less expensive to manufacture, while at the same time having the advantages of increased ruggedness and durability. Further objects and advantages will be indicated in the following detailed specification.

My invention is shown in illustrative embodiment in the accompanying drawing, in which:

FIGURE 1 is a side elevational view showing a grease gun of the kind with which my plunger assembly can be used, part of the grease gun barrel or cylinder being broken away to show the plunger assembly;

FIGURE 2, a transverse sectional view taken on line 22 of FIG. 1;

FIGURE 3, an enlarged sectional view showing the plunger assembly within the grease gun cylinder;

FIGURE 4, a plan view of a die-cut metal sheet, comprising the blank from which the guide element of the plunger assembly is formed;

FIGURE 5, another plan view of the blank of FIG. 4 illustrating the next stage in the forming of the guide;

FIGURE 6, an end view of the blank showing the guide at the same stage as shown in FIG. 5;

FIGURE 7, an elevational view of the completed guide;

FIGURE 8, a perspective view of one of the metal disks used in the plunger assembly;

FIGURE 9, a perspective view of a disk insert which is employed in conjunction with the disk of FIGURE 8;

FIGURE 10, a perspective view of the combined disk and disk insert;

FIGURE 11, a perspective view of the guide;

FIGURE 12, a perspective view of the other disk element;

FIGURE 13, a perspective view of the components of the plunger assembly, showing the parts in separated relation; and

FIGURE 14, an enlarged fragmentary sectional view showing the cap portion of the grease gun of FIG. 1 with the guide releasably locked thereto.

Looking first at FIG. 1, there is shown a grease gun having a barrel or cylinder 10, for holding the grease to be dispensed, as indicated at G. The gun also includes a dispensing head 11 which provides the high pres sure cylinder and lever-operated piston for dispensing the grease. On the rear of the gun is mounted an elongated closure cap 12. Extending through cap 12 and within barrel 1! there is a plunger rod 13, the plunger rod having a handle 14 mounted on its rearwardly projecting end. The construction and operation of these parts is shown in greater detail in my copending application Serial No. 785,689.

Within barrel and arranged for cooperating with piston rod 13, there is provided in accordance with the present invention the plunger assembly, which is designated generally by the letter A. In the illustration given, assembly A is backed up by a compression spring 15, the spring being arranged to urge assembly A toward dispensing head 11. If desired, however, spring 15 can be omitted. Assembly A will move forwardly toward the dispensing head by the suction created as the grease is dispensed, and also as will subsequently be described, plunger rod 13 can be engaged with assembly A for advancing, retracting, or rotating the assembly.

Turning now to FIG. 3, which shows the plunger assembly A in section, it can be seen that the assembly comprises a sealing member, designated generally at 16, a pair of disks 1'7 and 18, a disk insert 19, and a guide tube 20. The sealing member 16 includes an outer annular portion 21 for sealingly engaging the inner wall of the grease gun cylinder 10, or the inner wall of the grease cartridge, as explained in greater detail in application Serial No. 785,689. Sealing member 16 also provides a transversely-extending web portion 22, and a hub portion 23. Preferably, sealing member 16 is formed of a flexible, resilient material such as natural or synthetic rubber, and is formed in one piece by a molding operation.

In the illustration given, hub 23 projects rearwardly from web 22, and provides an opening 24 extending therethrough for slidably receiving plunger rod 13. As indicated in FIG. 3 and shown more clearly in FIG. 13, web 22 provides a plurality of spaced openings 25 which extend through the web. The purpose of these openings, which is one of the important features of the present invention, will now be explained.

In accordance with the present invention, at least one of the disks 17 or 18 could provide a plurality of projections aligned with and extending into the openings 25 of web 22. The disk projections should be dimensioned and arranged so as to be in contact with the upper disk through the openings, thereby permitting the contacting portions of the disks to be united by fusion. Preferably, the disks 17 and 18 are constructed of metal, and are each provided with complementary projections. In the illustration given, the web 22 provides three openings 25, and therefore disk 17 provides three projections 26, while disk 18 provides three projections 27. In FIGS. 12 and 13, the projections 27 are seen from the rearward side of the disk 18 and therefore appear as depressions. Disk 18 also provides rearwardly extending projections 28, the purpose of which will subsequently be explained.

The complementary projections 26 and 27 are arranged to extend into web openings 25 and to contact each other when the web 22 is sandwiched between the disks 17 and 18. This permits the projections of the metal disks to be connected by projection welding, as indicated at 29 in FIG. 3. If desired, other means can be provided for securing the disks and sealing member in fixed relation to each other.

As shown more clearly in FIGS. 3 and 8, the forward disk 17 provides an integral central portion 30* which projects outwardly therefrom away from web 22 and hub 23 to provide a partially enclosed recess 31 (FIG. 3). As indicated in FIG. 3 and shown more clearly in FIG. 8, the projecting central portion 30 is provided with a central opening 32 dimensioned for slidably receiving rod 13. Preferably, there is also provided at least one slot extending laterally from the opening 32. In the illustration given, there is provided a pair of oppositely disposed slots 33. The slots 33 cooperate with the oppositely disposed, laterally extending pins 34, which are provided at the forward end of rod 13, as shown in FIG. 3. By withdrawing rod 13, the pins 34 can be drawn into recess 31 through slots 34, and then by rotating the rod until the pins 34 are offset from the slots 33, the plunger assembly A can be advanced or retracted by means of handle 14.

In the illustration given, the central portion of disk 17 also provides a pair of oppositely disposed, rearwardly extending projections 35, as shown in FIG. 8. These projections act as stops or abutments by engaging the pins 34 and preventing further rotation of rod 13 relative to plunger assembly A. With this arrangement, when desired, handle 14 can be employed to rotate the plunger assembly within barrel 10.

In the illustration given, recess 31 is backed up with a disk insert 36, this insert being shown in perspective in FIG. 9. Insert 36 is dimensioned so that it will cover the rear side of recess 31 and bear against the portion of disk 17 just outwardly of the recess, thereby permitting the insert 36 to be connected to disk 17 by spot welding, as indicated in FIG. 3. The assembled insert and disk are shown in perspective in FIG. 10.

To facilitate the entry of pins 34 into recess 31, the insert 36 is provided with a pair of oppositely disposed, I

rearwardly extending depressions 37. The insert disk is also provided with a central opening 38 for slidably receiving rod 13. If desired, oppositely disposed notches 39 can be provided to permit the insert 36 to straddle the projections of the disk 17.

Preferably, the opening 24 in hub 23 is dimensioned so that rod 13 is slidable therein while providing a substantially grease-tight seal between the rod and hub. This will prevent grease from bypassing sealing member 16 by flowing along rod 13. For this reason, it is desirable to have the flexible, resilient hub 23 in direct contact with rod 13. This construction, however, creates a problem since the flexible, resilient nature of the hub 23 might permit the plunger assembly A to become canted within the barrel 10. It is therefore desirable to provide an auxiliary guide means, such as the guide tube 29, for maintaining the alignment of rod 13 and plunger assembly A.

In the illustration given, guide tube 2% is disposed about rod 13 in axial alignment therewith, the internal diameter of the guide tube being considerably larger than the external diameter of the rod, as shown more clearly in FIG. 3. In the illustration given, tube 2%) is made sufficiently large that it also extends over hub 23, and bears against the rear face of disk 18. The inner end of tube 20 provides a plurality of integral, laterally extending tabs 40, which are connected to disk 18 by spot or pro jection welding, as indicated in FIG. 3.

The outer portion of tube 24 provides a pair of oppositely disposed, inwardly turned guide brackets 41. The inner ends of guide brackets 41 have complementary recesses 42, which together provide a guide bearing for slidably receiving one plunger rod 13, as shown more clearly in FIG. 2. In the illustration given, brackets 41 are integral with tube 20, being struck out of the walls of the tube and folded inwardly.

One method of forming guide tube 20 is illustrated in FIGS. 4-7. In FIG. 4, there is shown a die-cut blank B which has been formed from a piece of sheet metal stock, such as low carbon steel. In the next step, as shown in FIG. 5, the tabs 40 are folded outwardly at right angles to the blank B, and the brackets 41 are folded in the opposite direction at somewhat less than at right angles to the blank. The results of these folding operations are shown more clearly in FIG. 6. In this step, the rounding of the blank to a tubular shape is begun, the side edges being rolled to the configuration shown in FIG. 6. As a final step, the blank B is formed to the tubular shape of guide 20, as indicated in FIG. 7, and the brackets 41 are brought into meeting relation at right angles to the axis of the tube 20, as indicated by the dotted lines in FIG. 7. If desired, the tabs 40 can be provided with projections, as indicated, to facilitate the attachment of the guide 20 to the disk 18 by a projection welding procedure.

In the illustration given, the rearward end of tube 20 provides latch means integral therewith for cooperating with the rear cap 12 of the grease gun to hold the Plunger assembly in retracted position, as shown more clearly in FIG. 14. More specifically, the rear end of guide tube 29 provides a pair of cars 43, with the ears having an arcuate shape. The rear wall of cap 12 provides a pair of arcuate slots 44 which are alignable with ears 43 and are arranged to cooperate therewith. The ears are undercut, as indicated at 45, for interlocking with raised areas 46 which lie adjacent the ends of slots 44. Plunger assembly A may be drawn rearwardly until the ears 43 extend through the slots 44, and then the plunger assembly can be slightly rotated so that the ears rest on the raised areas 46, thereby releasably locking the plunger assembly in the withdrawn position. The plunger assembly can be released by forcibly rotating the ears 43 in the opposite direction to bring them into alignment with the slots 44.

As also shown in FIG. 14, the rearward projections 23 of disk 18 cooperate with complementary projections 47 of sealing member 16. Thus, the projections 28 and 47 provide additional means for holding the disks in fixed alignment with the sealing member. The rearwardly extending disk projections 28 also perform an additional function. As indicated in FIG. 14, the forward end of the spring 15 bears against the outermost portions of the projections 23, and this serves to hold the spring in centered relation with respect to the plunger assembly A.

With respect to the control of the plunger assembly A by means of handle 14- and rod 13, it will be noted (FIG. 14) that the depressions 37 in insert 36 are arranged in alignment with the slots 33 in disk 17. This permits the pins 34 which extend laterally from the forward end of rod 13 to enter the depressions 34 immediately after the pins are drawn rearwardly through the slots 33. By continuing to pull back on the plunger against the spring, the entire plunger assembly can be rotated sufliciently to hook and unhook the ears 43.

Also, as shown in FIG. 14, the opening 24 through the hub 23 of sealing member 16 preferably has a central enlargement as indicated at 48. In this arrangement, the internal diameter of opening 2'4 adjacent the upper and lower ends of hub 23 can be made slightly smaller than the external diameter of rod 13, thus assuring a greasetight seal between the hub and the rod. By providing the central enlargement 48, too much friction between the rod and the hub is avoided, which facilitates the sliding of the rod with respect to the sealing member while at the same time maintaining a grease-tight seal.

While in the foregoing specification the various features of the present invention have been described with relation to a specific embodiment thereof, as shown in the grease gun and plunger assembly of the accompanying drawings, it will be apparent to those skilled in the art that the features of the present invention are adapted for use in grease guns which differ in construction from the one shown in the drawings, and that a number of constructional details of the plunger assembly can be varied without departing materially from the present invention.

I claim:

In a grease gun plunger assembly, the combination comprising a sealing member of flexible, resilient, nonmetallic material, said sealing member providing an outer annular portion, a transversely-extending web portion, and a central hub portion, said annular portion being adapted for engaging the walls of a cylindrical grease container, said hub portion providing an opening therethrough for slidably receiving a grease gun plunger rod, a pair of metal disks arranged so that said web portion is sandwiched therebetween, means for securing said disks and said sealing member in fixed relation to each other, and an elongated tubular guide mounted on one of said disks to extend away from said web and hub portions, the internal diameter of said guide being greater than said hub portion and the innermost portion of said guide enclosing said hub portion, the end of said guide adjacent said one of said disks providing tabs bearing against said one disk and being united thereto, the outer portion of said tubular member providing a pair of oppositely-disposed, inwardly-turned guide brackets, the inner ends of said guide brackets having complementary recesses which together provide a guide bearing for slidably receiving the said plunger rod.

2. The combination of claim 1 wherein said guide is formed from sheet metal stock, and wherein the outer end of said guide provides latch means integral therewith for cooperating with the rear cap of a grease gun to hold said plunger assembly in retracted position.

3. In a grease gun plunger assembly, the combination comprising a sealing member of flexible, resilient, nonmetallic material, said sealing member providing an outer annular portion, a transversely-extending web portion, and a central hub portion, said annular portion being adapted for engaging the walls of a cylindrical grease container, said hub portion providing an opening therethrough for slidably receiving a grease gun plunger rod, a pair of metal disks arranged so that said web portion is sandwiched therebetween, and means for securing said disks and said sealing member in fixed relation to each other, said hub portion extending through the central opening in one of said disks, the other of said disks providing an integral central portion projecting outwardly therefrom away from said hub portion to provide a partially enclosed recess, the central opening of said other disk being provided by the outwardly projecting central portion thereof, said central portion also providing at least one slot extending laterally from one side of the said central opening therein, whereby a forward end of the plunger rod having a lateral projection can be releasably engaged with said assembly for urging said assembly in either direction, and a third metal disk positioned to extend across the side of said recess adjacent said hub, said third disk being united to said other disk by fusion and also providing a central opening therein for slidably receiving the same plunger rod.

4. The combination of claim 3 wherein means is provided within said recess angularly offset from said slot for engaging the said plunger rod pin so that said plunger assembly can be rotated by rotating said plunger rod.

5. In a grease gun plunger assembly, the combination comprising a sealing member of flexible, resilient, nonmetallic material, said sealing member providing an outer annular portion, a transversely extending web portion, and a central hub portion, said annular portion being adapted for engaging the walls of a cylindrical grease container, said hub portion providing an opening therethrough for slidably receiving a grease gun plunger rod, a pair of metal disks arranged so that said web portion is sandwiched therebetween, each of said disks having a central opening therein, said sealing member Web portion having a plurality of spaced openings extending therethrough, at least one of said disks providing a plurality of projections aligned with and extending into the said openings in said Web portion, said projections through said openings being in contact with the other of said disks and being united thereto by fusion, and an elongated tubular guide mounted on one of said disks to extend away from said web and hub portions, the internal diameter of said guide being greater than the diameter of said opening in said hub portion and the innermost portion of said tubular member enclosing said hub portion, the end of said guide adjacent said one of said disks providing integral, laterally-extending tabs bearing against said one disk and being united thereto by fusion.

6. The combination of claim 5 wherein the outer por tion of said guide provides a pair of oppositely-disposed, inwardlydurned guide brackets, the inner ends of said guide brackets having complementary recesses which to gether provide a guide bearing slidably receiving the plunger rod.

7. The combination of claim 6 in which said tubular guide member is formed from sheet metal stock, and in which said guide also provides latch means integral therewith for cooperating with the rear cap of said grease gun to hold said plunger assembly in retracted position.

References Cited in the file of this patent UNITED STATES PATENTS 2,408,346 Smith Sept. 24, 1946 2,409,619 Fitch Oct. 22, 1946 2,687,097 Engseth Aug. 24, 1954 

